Method and apparatus for freeing of and preventing formation of paraffin and asphaltand like obstructions in oil wells, natural gas wells and the like



March 2, 1960 F. .1. HURLSTONE ETA METHOD AND APPARATUS FOR FREEING OF AND PREVENTING 0F PARAF'FIN AND ASPHALT AND LIKE OBSTRUCTIONS IN OIL WELLS, NATURAL GAS WELLS AND THE LIKE Filed Jan. 3, 1957 3 Sheets-Sheet l r A 7 1 \J k I Z 5, H -W rn JM 0 A 4 w A .,4,D--,,,n.g,wmV/. |Y (I! n B 1 1|! \l! z A 6 97 A/WIY m w a 6 w Ai- W A 6 a 6 a 6 W w z March 22, 1960 F. J. HURLSTONE ETAL 2,929,451

METHOD AND APPARATUS FOR FREEING OF AND PREVENTING FORMATION OF PARAFFIN AND ASPHALT AND LIKE OBSTRUCTIONS IN OIL WELLS, NATURAL GAS WELLS AND THE LIKE Filed Jan. 3, 1957 3 Sheets-Sheet 2 INVENTOR5 l'azau 1% 2,929,451 FORMATI F. J. HURLSTONE FI'AL 'I'US FOR FREEING 0F March 22, 1960 METHOD AND APPARA AND PREVENTING 0F PARAFFIN AND ASPHALT AND LIKE OBSTRUCTIONS IN OIL WELLS, NATURAL GAS WELLS AND THE LIKE Filed Jan. 3, 195'? 3 Sheets-Sheet 1 1%;??? avffarg/ dflaskazvz,

u 7 7 if" United States Patent METHOD AND APPARATUS FOR FREEING OF AND PREVENTING FORMATION OF PARAFFIN AND ASPHALT AND LIKE OBSTRUCTIONS IN BIL WELLS, NATURAL GAS WELLS AND THE IKE Frank J. Huristone and Harry A. Musham, Chicago, Ill. Application January 3, 1957, Serial No. 632,297 15 Claims. (Cl. 1664I) This invention relates, in general, to a method and apparatus for freeing oil wells, natural gas wells and the like from obstruction, and for inhibiting formation of paraflin and oleaginous and like blocks therein.

It is well known that the accumulation and/or congealing, stilfening, solidification or hardening of paraftin, or other hydrocarbons or waxy or similar substances on the walls of the well tubings and casings, or on other producing portions of the well, or along the crevices and fissures of the well cavity, clogs, or chokes the bore of the pump and its valves, as well as the well tubing and casing and the crevices and fissures of the fluid producing stratum. This causes the flow of oil, natural gas, or the like to be impeded and decreased, thereby decreasing the production of the well, and often to stop or cease entirely.

Heretofore, deparaffining of the tubings, casings or other parts of the well has been a laborious and costly matter. It has usually been accomplished in actual practice by lifting out the lengthy pumping rod and the plunger and valves, in the case of pumped wells, and in the case of both pumped and free flowing wells, by the introduction of scrapers of various forms to free the parafiin or other obstructing material and for lifting the same to the surface.

Other ways of deparatfining wells have also been proposed including the introduction of a heated fluid down between the outer casing and the inner tubing of the well, but none of these has been generally adopted. They have not always provided for the effective melting or removal of the paraflin or other obstructing materials at all places where the objectionable choking or clogging occurs. This is necessary, since obstruction, choking or clogging at any place along the path of the flow of oil will impede and decrease and often stop the fiow of oil, natural gas or the like, entirely.

One of the main objects of our present invention is to provide an improved method and apparatus for freeing oil wells, natural gas wells and the like from obstruction, which method and apparatus will overcome the shortcomings and difficulties of prior practices and proposals.

Another object is to provide a method and apparatus wherein heated fluid is forced downwardly through a tube at the axis of the well casing, this heated fluid being discharged from the tube near the lower end thereof and utilized to melt the obstructing material, and wherein the melted obstructing material is allowed to flow upwardly and outwardly from the well through a space between the tube and the well casing with the fluid production from the well.

Another object is to provide a method and apparatus wherein there is a hollow pumping rod spaced within the tubing and having vertical reciprocating action therein and wherein the heated fluid is forced downwardly through the pumping rod.

Another object is to provide apparatus of the aforementioned character wherein the obstruction melting fluid is heated and pressurized by a compressor having a flexible by-pass connection with the interior of the upper end of the hollow pumping rod which permits reciprocating action of the pumping rod in the tubing.

Another object is to provide a method and apparatus wherein the heated fluid is forced downwardly not only through the hollow interior of the pumping rod, but also through a space between the well casing and the tubing, and wherein at least the heated fluid discharged from the lower end of the space between the well casing and the tubing is delivered into the fluid production stratum of the well to heat the same and the crevices and fissures thereof.

Another object is to provide a method and apparatus wherein the heated obstruction melting fluid is of noninflammable character.

Another object is to provide a method and apparatus wherein the obstruction melting fluid is heated and pressurized by a compressor for forcing the fluid down into the well.

Another object is to provide a method and apparatus wherein the hollow pumping rod is provided at its lower end with a plunger having internally thereof an upwardly seating valve and means for yieldingly seating this valve upon a predetermined drop in pressure of the heated fluid forced downwardly through the pumping rod.

Another object is to provide a method and apparatus wherein the aforementioned plunger at the lower end of the hollow pumping rod has a tubular body provided with ports opening generally radially outwardly into space between the tubular body and the tubing at a position below a seat for the valve.

Another object is to provide a method and apparatus wherein an adjustable abutment for the yielding seating means is threaded into the tubular plunger body, and wherein the tubular plunger body has drainage outlets below this abutment.

Further objects and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings, it being understood that the invention is limited only within the scope of the appended claims and not to the particular embodiments selected for illustration.

In the drawings:

Figure l is a more or less schematic vertical axial sectional view of the head or outer portion of a pumped well equipped with means for carrying out the present inven tion;

Figure 2 is a fragmentary vertical axial sectional view the foot or inner end of the well shown in Figure 1; Figure 3 is a fragmentary vertical axial sectional view through a tubular fitting between the lower end of the pumping rod and the plunger thereon, with the valve in this fitting in open position;

Figure 4 is a fragmentary vertical axial sectional view similar to Figure 3 but with the tubing and well casing omitted and the valve in closed position;

Figure 5 is a detail section taken on the line Figure 4; and

Figure 6 is a schematic axial sectional view showing certain aspects of the present invention applied to a free flowing well.

Referring now to Figures 1-5 of the drawings, the well selected for illustration, comprises a tubular well casing 1 extending from above the surface 2 of the ground 3 down, for example, through impervious rock 4 approximately to the well cavity, or fluid, such for example, as oil producing stratum 5. impervious rock 6 is shown underlying the fluid producing stratum 5 but this and the other aspects may vary within the scope of the present invention. At ground level the casing 1 may, for no ample, be cemented in the ground at 6, although this too may vary.

Spaced within the casing 1 is the tubing 7. This tubing 7 extends downwardly through the casing 1 approximately to the oil or other fluid producing stratum 5. The upper end of the tubing 7 passes upwardly through the upper end of the casing 1, which is closed by the usual or any suitable closure ii. The lower end of the tubing 7 may be provided with a perforated sleeve 7', approximately at the oil or other fluid stratum 5.

A hollow pumping rod is spaced witi iu the hing 7 and has vertical reciprocating action therein. The upper end of the rod 9 passes upwardly through the upper end of the tubing 7 which is closed by a suitable closure 10. The upper end or head 11 of the rod 9 is operatively connected with suitable lever mechanism, or a pumping jack 12, which may be of any well-known or suitable form, and which operates or reciprocates the pumping rod 9 and plunger thereon, to be presently described, to elevate, for example, the oil from the well. Below the closure the tubing 7 has generally horizontal outlet tubes or conduits 13 for discharging the oil, or other fluid, from the well. These outlets 13 may be controlled by valves (not shown) as well known in the art.

The lower end of the well casing 1 may have a perforated sleeve 14 with the perforations or openings therethrough, shown at 15. This perforated sleeve 14 is shown positioned in the oil, or other fluid producing stratum 5. Screwed at 16 into the lower end of the hollow rod 9 is the reduced diameter upper end of a tubular fitting or valve body 17. This fitting 17 is screwed at its lower end at 18 upon the reduced diameter upper end of the head of the pump plunger 19 which may be of any well known or suitable form. The plunger 19 may, for

example, have a double valve arrangement therein (not shown) for taking in oil from the producing stratum 5 and expelling or discharging the same through the plunger openings 20 into the annular space 21 between the pumping rod 9 and tubing 7 for elevation through the space 21 to the outlets 13.

Within the tubular body of the fitting 17 is a valve having a valve head 22 provided with a valve stem 23. The lower end of the stem 23 operates slidingly in a ring 24, which is screwed at 25 into the fitting body 17 and forms an abutment for a valve spring 26 and a guide for the lower end of the valve stem 23. The valve spring 26 is disposed within the fitting 17 and confined endwise between the nbutmcnt or ring 24 and the head 22 of the valve. In the case of gas expansion, the pressure drops and th: spring 26 seats the valve head 22 against 1 valve seat 28 to shut off the lower end of the hollow interior of the pumping rod 9 to prevent possible freezing or choking of the pump.

Above the valve head 22, in its lower or open position, as shown in Figure 2, the tubular wall of the fitting 17 is provided with openings or ports 29 opening generally radially outwardly into the space 21. For the purpose of assuring drainage of any fluid accumulation from the interior of the fitting 17, the wall of this fitting is provided with drainage outlets 30 opening from the interior of the fitting 17 below the ring or abutment 24 into the annular space 21.

With the apparatus as thus described, and the use therewith of a hollow pumping rod 9, the present invention provides a compressor or other fluid pressurizing means 32 supported, for example, on a base 33 mounted in or on the ground 3. The compressor 32 has an inlet 34 for receiving the obstacle freeing fluid, which, in the broader aspects of the invention, may be any suitable gas or any mixture of gases, air, for example. In the more specific aspects of the invention, the fluid delivered into the inlet 34 is preferably a fluid, such as Freon 12, or the like, which is non-inflammable or will not support com bustion or a mixture therewith. This is desirable, since it eliminates any fire hazard at or within the well. While carbon dioxide may, in a measure, be suitable, within the broader aspects of the invention, it cools rapidly on expansion and may, therefore, lower the temperature at, for example, a paraffin block in the well, so as, under some conditions, to freeze the paraffin harder than it was before introduction of the paratfin melting fluid.

The compressor outlet 36 is connected by a pipe or tube 37 with the upper end of the annular space 38 between the casing 1 and tubing 7. The pipe 37 is fitted with a coupling 39 and provided with valves 40 to regulate the flow of obstruction melting fluid into the space 38.

Leading from the pump outlet 36 or pipe 37, is a second connection for delivering obstruction melting fluid into the upper end of the internal passage 42 within the hollow pumping rod 9. This second connection is in the form of a flexible by-pass conduit 43, the flexibility of which permits the vertical reciprocating action of the pumping rod 9 and its plunger in the tube 7. The flexible conduit 43 is provided with valves 44 and 45 for regulating the flow of obstruction melting material into the upper end of the interior of the hollow pumping rod 4. The second connection may also have couplings 46 and 47 with the flexible conduit portion 43 of this connection extending only between these couplings and with the connection portions at the ends of the flexible conduit of rigid form.

The compressor 32, and its driving motor or engine (not shown) may be mounted on a permanent base on a part of the pumping engine base, or on a portable base or skids, or on a truck with wheels for moving it about (all not shown).

In the operation of the apparatus shown in Figures l-S, the parafiin or other obstruction melting or liquefying fluid is admitted to the compressor 32 through its inlet 34. In Figure 1 an inverted bottle of liquid Freon 12 has its outlet 61 in screwed or threaded connection with the outer end of a coil 62 or with a suitable fitting between the outlet 61 and the outer end of the coil 62. The opposite end of the coil 62 is screwed or otherwise opens into a reduced opening at the inlet 34 of the compressor 32. An open ended sleeve 64 surrounds the coil 62 and a fan or impeller 65 driven, for example, by the driving motor or engine for the compressor 32 circulates air through the sleeve 64 and around the coil 62. The Freon 12 liquid is gasified in the coil 62 and passes into the inlet 34 of the compressor.

Freon, as well understood in the art, is a group of fluorochloromethanes and ethanes, whereas, Freon 12 is dichlorodifluoromethane.

The compressor 32 pressurizes the fluid sufiiciently to force it downwardly through any pressure of the oil or other fluid production from the well. The compressor 32 is preferably suitably insulated and also, in pressurizing the fluid, heats the same by adiabatic compression, preferablv to the melting or liquefication temperature of the paraffin or other obstructing material.

The obstruction melting fluid thus heated and presurized is forced downwardly through both the annular space 33 between the well casing 1 and the tubing 7 and through the hollow interior 42 of the pumping rod 9. This fluid is discharged from the lower end of the casing 1 and through the perforated sleeve 14 into the oil producing stratum 5, to heat the same and melt ratfin or the like in the crevices and fissures thereof. Simultaneously the obstruction melting fluid is discharged from the lower end of the hollow pumping rod 9, and, as suming! that the valve head 22 is open, through the ports 2? into the space 21. Adequate or abundant supply of heated fluid to all parts of the well subject to obstruction is thus assured.

The melted or liquefied parafiin flows upwardly and outwardly from the well through the space 21 between the pumping rod 9 and the tubing 7 with the oil or other fluid production from the well and is discharged with the oil or other fluid production through one or more of the outlet tubes 13. The compressor 32 may be driven by a steam, diesel or gasoline engine, or by an electric motor or other suitable driving means. We also contemplate driving the compressor 32 through a geared connection with the engine or driving means for the rocking beam or pumping jack 12.

The heat transmitted from the heated fluid in the casing 1 through the tubing 7 and that from the hollow pumping rod 9 is absorbed by the flowing or pumped up oil in the tubing 7 and will be at a higher temperature than that required to liquefy any paraffin particles that form in the tubing and which may be deposited and adhere to the inner surface of the tubing and the outer surface of the pumping rod, which may otherwise impede or block the flow of oil in the case of a pumped well. In this manner the formation of paraifin is inhibited and the viscosity of the oil reduced as are also the friction losses in the tubing. The work done in pumping a well and its cost can be reduced, effecting a saving in operation costs.

in the case of pump stoppage caused by the formation and deposition of paralfin, the hot compressed fluid is injected in both the casing and the pump rod and kept there until the pumping rod and its plunger are released by the melting of the paraffin by its mingling with the oil in the tubing. This resumes operation of the application of force by the rocker beam or other type of means for reciprocating the pumping rod and, as already pointed out, the melted or liquefied paraflin or the like is removed from the tubing in the stream of oil flowing therefrom.

In case the compression or pressure of the heated fluid should become insufficient to overcome all resistance to its passage down through the pump rod and down through the casing to the bottom of the well, the valve head 22 is moved to closed position by the spring 26 as shown in Figure 4 this prevents cooling of the heated fluid with resulting solidification of the paraffin or the like and blocking or choking of the well on this account.

In the case of a free flowing well, as shown in Figure 6, freezing of a blocked well and inhibition of the well against blocking, is accomplished by introducing the inner end of a flexible tubing or hose 50, connected with the compressor or pressurizing means, down axially through the well casing 1' into the coagulated mass of oil, or other produced fluid and paraflin, or other blocking material. The flexible tubing or conduit 50 enters this well through an angular elbow 51 on the casing or tubing 1. The elbow 51 is provided with a valve 52 for shutting off or closing the elbow 51 when the flexible tubing 50 is not in place. The valve 52 may also be arranged, or other valve means provided, for regulating the flow of heated fluid down through the conduit 50. The lower end of the conduit 50 is open and disposed in the oil or other fluid stratum.

In the embodiment of the invention shown in Figure 6 the heated fluid comes in contact with the top of any paraifln or like block and gradually melts it through to the liquid oil below it. The melted or liquefied paralfin or the like passes back into the oil or other fluid and is forced to the head of the tubing or casing with the oil or other fluid by the natural pressure in the oil or other fluid itself. The free flow of oil is thus resumed and the flexible conduit 50 may be withdrawn and the slot valve 52 closed, the oil or other produced fluid passing out through the outlet (not shown) at the head of the casing or tubing 1'.

The arrangement shown in Figure 6 can be designed for insertion of the tubing or conduit 50 down through the head of the casing or tubing 1' to permit insertion of the flexible tubing into the space between the casing and the oil tubing.

It is to be understood that the elbow 51 opens into the tubing 1' above the ground in What is called the Well head. it is to be further understood that below the ground the tubing 1 extends down through the usual enter well casing with space between the tubing 1' and the casing.

Instead of employing an elbow and flexible tubing, as shown in Figure 6, we further contemplate a rigid inner tubing (not shown) within the tubing 1', through which the obstacle freeing and inhibiting fluid may flow downwardly to the blocking material. The head or closure of the oil tubing in such case may have an opening through which the inner rigid tubing may pass axially from the upper end of the tubing 1'. The inner rigid tubing may be made of rigid pipe sections suitably joined together.

The embodiments of the invention shown in the drawings are for illustrative purposes only and it is to be expressly understood that said drawings and the accompanying specification are not to be construed in a definition of the limits or scope of the invention, reference being had to the appended claims for that purpose.

We claim:

1. Apparatus for removing solidified waxy-like substances from an oil well having an outer tubular well casing for extension from above the surface of the ground downwardly approximately to the oil producing stratum, a tubing extending downwardly substantial concentrically within said well casing from the upper end thereof approximately to the oil producing stratum and defining with said well casing a first annular space opening downwardly from approximately the upper end of said well casing to the oil producing stratum, a hollow pumping rod disposed substantially concentrically within said tubing and defining with said tubing a second annular space opening dowwardly from approximately the upper end of said tubing to the oil producing stratum, said pumping rod having reciprocating action in said tubing and the hollow interior thereof opening downwardly from approximately the upper end of said rod to the oil producing stratum, pressurizing and heating means for pressurizing and heating a fluid to the melting temperature of the waxylike substance, said pressurizing and heating means having a discharge outlet opening into both the upper end of said first annular space and the upper end of the hollow interior of said pumping rod for delivery of the pressurized and heated fluid downwardly through two annular concentric paths and into the oil producing stratum at the bottom of the well, and at least one outlet opening from the upper end of said tubing for discharge of melted waxy-like substance and oil discharged upwardly from the oil producing stratum through said second annular space.

2. Apparatus according to claim 1 wherein the opening of the discharge outlet of the pressurizing and heating means into the upper end of the hollow interior of the pumping rod includes a flexible connection permitting reciprocating action of said pumping rod in said tubing.

3. Apparatus for removing solidified waxy-like substances from an oil well having an outer tubular well casing for extension from above the surface of the ground downwardly approximately to the oil producing stratum, a tubing extending downwardly substantially concentrically within said well casing from the upper end thereof approximately to the oil producing stratum and defining with said well casing a first annular space opening downwardly from approximately the upper end of said well casing to the oil producing stratum, a hollow pumping rod disposed substantially concentrically within said tubing and defining with said tubing a second annular space opening downward'y from approximately the upper end of said tubing to the oil producing stratum, said pumping rod having reciprocating action in said tubing and the hollow interior thereof opening downwardly from approximately the upper end of said rod to the oil producing stratum, a compressor having an inlet and a discharge outlet, a coil having one end opening into the inlet of said compressor, an inverted liquid containing vessel having an outlet opening into the other end of said coil for gasification of the liquid in said coil and delivery into said compressor for heating by adiabatic compres sion therein, connections between the discharge out'et of said compressor and both the upper end of said first annular space and the upper end of the hollow interior of said pumping rod for delivery of pressurized and heated fluid downwardly through two concentric paths and into the oil producing stratum at the bottom of the well, and at least one outlet opening from the upper end of said tubing for discharge of melted waxy-like substance and oil discharged upwardly from the oil producing stratum through said second annular space.

4. Apparatus for removing solidified waxy-like substances from an oil well having an outer tubular well casing for extension from above the surface of the ground downwardly approximately to the oil producing stratum, a tubing extending downwardly substantially concentrically within said well casing from the upper end thereof approximately to the oil producing stratum and defining with said well casing a first annular space opening downwardly from approximately the upper end of said well casing to the oil producing stratum, a hollow pumping rod disposed substantially concentrically within said tubing and defining with said tubing a second annuIar space opening downwardly' from approximateiy the upper end of said tubing to the oil producing stratum, said pumping rod having reciprocating action in said tubing and the hollow interior thereof opening downwardly from approximately the upper end of said rod to the oil producing stratum, pressurizing and heating means for pressurizing and heating a fluid to the melting temperature of the waxy-like substance, said pressurizing and heating means having a discharge outlet opening into both the upper end of said first annular space and the upper end of the hollow interior of said pumping rod for delivery of the pressurized and heated fluid down wardly through two concentric paths and into the oil producing stratum at. the bottom of the wel at least one outlet opening from the upper end of said tubing for discharge of melted waxy-like substance and oil discharged upwardly from the oil producing stratum through said second annular space, a plunger on the lower end of said hollow pumping rod and provided internal y thereof with an upwardly seating valve, and means for yie dingly closing said valve upon a predetermined drop in pressure of the heated fluid forced downwardly through said pumping rod.

5. Apparatus according to claim 4 wherein the plunger has a tubular bcdy provided with ports opening generally radially outwardly into space between the tubular body and the tubing at a position below a seat for the valve.

6. Apparatus according to claim 4 wherein the plunger has a tubular body provided with ports opening generally radially outwardiy into space between the tubular body and the tubing at a position below a seat for the valve, means for yieldingly closing said valve upon a predetermined drop in pressure of the heated fluid forced downwardly through said pumping rod, and an adjustable abutment for said yielding valve clcsing means threaded into the tubular body, said tubular body having drainage outlets below said abutment.

7. The method or maintaining the upwardly discharging oil of an oil well at such a temperature as will prevent solidification of hydrocarbon partic'es in the oil and accompanying obstruction of the oil discharge, which comprises. heating a fluid to the melting temperature of the hydrocarbon particles, simultaneously circulating the heated fluid downwardly through two concentric paths and throughout the upright extent of the discharging oil aon which solidification of such particles may occur, and t1 irging the oil and melted hydrocarbon material upwardly between the concentric streams of heated fluid, whereby to prevent solidification of the hydrocarbon material throughout the upright extent of the discharging oil and hydrocarbon material along which such solidification of such particles may occur.

8. The method according to claim 7 wherein the concentric streams of heated fluid are disposed substantially axially and in surrounding re ation, respectively, wiLh re spect to the discharging stream of oil and hydrocarbon material.

9. The method according to claim 7 wherein the heated fluid is from the group of fluorochloromethanes and flnorochloroethanes.

10. The method according to claim 7 wherein the heated fluid is dichlorodifluoromethane.

ll. The method of maintaining the upwardly discharging oil of an oil well at such a temperature as will prevent so'idification of hydrocarbon particles in the oil and accompanying obstruction of the oil discharge. which comprises, pressurizing a fluid from the group of fluorochloromethancs and fluorochloroethanes to heat the same by adiabatic compression to the melting point of the hydrocarbon particles, simultaneously circulating the heated fluid downwardly through two concentric paths and throughout the upright extent of the discharging oil along which solidification of such particles may occur, and discharging the oil and melted hydrocarbon material upward.y between the concentric streams of heated fluid, whereby to prevent solidification of the hydrocarbon material throughout the upright extent of the discharging oil and hydrocarbon material along which such solidification of such material may occur.

12. The method according to claim 7 wherein the heated fluid is one that is non-inflammable and will not condense.

13. The method of maintaining the oil producing stratum and the discharging oil of an oil well at such a temperature as will prevent solidification of hydrocarbon particles in the oil and accompanying obstruction of the oil discharge, which comprises, heating a fluid to the melting temprrature of the hydrocarbon particles, simultaneously circulating the heated fluid downwardly through two concentric paths and to an oil producing stratum at the bottom of the well to melt any solidified hydrocarbon particles in said oil producing stratum, and discharging the oil and melted hydrocarbon material upwardly between the concentric streams of heated fluid whereby to prevent solidification of the hydrocarbon material along the upright discharge path of the oil and said hydrocarbon material.

14. The method of maintaining the upwardly discharging oil in the upright oil discharge tube of an oil well at such temperature as will prevent solidification of hydrocarbon particles in the oil and accompanying obstruction of the oil discharge, which comprises, heating a fluid to the melting temperature of the hydrocarbon particles, and circulating the heatzd fluid in direct contact with walls between which the oil is discharged upwardly and which walls have direct contact with the oil discharging through said tubing throughout the upright extent thereof along which solidification of such particles may occur to maintain the hydrocarbon material in fluid form for discharge with the oil.

15. Apparatus for removing solidified waxy-like substances from an oil well having an outer tubular well casing for extension from above the surface of the ground downwardly approximately to the oil producing stratum, a tubing extending downwardly substantially concentrically within said well casing from the upper end thereof approximately to the oil producing stratum, a hollow pumping rod disposed substantially concentrically within said tubing and defining with said tubing an annular space opening downwardly from approximately the upper end of the tubing to the oil producing stratum, said pumping rod having reciprocating action in said tubing and the hollow interior thereof opening downwardly from approximately the upper end of said rod to the oil producing stratum, pressurizing and heating means for pres- 9 10 surizing and heating a fluid to the melting temperature and oil discharged upwardly from the oil producing straof the waxy-like substance, said pressurizing and heating tum through said annular space. means having a discharge outlet opening into the hollow interior of said pumping rod for delivery of the pres- References Cited 111 file 0f ihls Patent surized and heated fluid downwardly through said rod 5 UNITED TA PAT N S and into the oil producing stratum at the bottom of the well, and at least one outlet opening from the upper end 1565574 Larsen 1925 of said tubing for discharge of melted waxy-like substance 2341573 Reed 1944 

7. THE METHOD OF MAINTAINING THE UPWARDLY DISCHARGING OIL OF AN OIL WELL AT SUCH A TEMPERATURE AS WILL PREVENT SOLIDIFICATION OF HYDROCARBON PARTICLES IN THE OIL AND ACCOMPANYING OBSTRUCTION OF THE OIL DISCHARGE, WHICH COMPRISES, HEATING A FLUID TO THE MELTING TEMPERATURE OF THE HYDROCARBON PARTICLES, SIMULTANEOUSLY CIRCULATING THE HEATED FLUID DOWNWARDLY THROUGH TWO CONCENTRIC PATHS AND THROUGHOUT THE UPRIGHT EXTENT OF THE DISCHARGING OIL ALONG WHICH SOLIDIFICATION OF SUCH PARTICLES MAY OCCUR, AND DISCHARGING THE OIL AND MELTED HYDROCARBON MATERIAL UPWARDLY BETWEEN THE CONCENTRIC STREAMS OF HEATED FLUID, WHEREBY TO PREVENT SOLIDIFICATION OF THE HYDROCARBON MATERIAL THROUGHOUT THE UPRIGHT EXTENT OF THE DISCHARGING 